1. Field of the Invention
The present invention relates to a structure of the electroluminescent display device.
2. Description of the Related Art
In recent years, an electroluminescent (hereafter, referred to as EL) display devices with an organic EL element have been receiving an attention as a display device substituting for a CRT and an LCD.
Since the organic EL element is sensitive to moisture, an organic EL display panel having the EL element thereon is covered with a metal cap or a glass cap coated with a desiccant, thereby inhibiting moisture infiltration. FIG. 5 is a cross-sectional view of a structure of a conventional organic EL display panel. A device glass substrate 100 has a display region having many organic EL elements (not shown) on a surface thereof. The whole surface of the display region is covered with a cathode 101 of the organic EL element. The cathode 101 is made of, for example, an Al (aluminum) layer. The device glass substrate 100 is mounted with a polarizer 102 on a back surface thereof.
The device glass substrate 100 of the above structure is attached to a sealing glass substrate 104 with sealing resin 103 made of an epoxy resin or the like. The sealing glass substrate 104 has a concave portion (hereafter, referred to as a pocket portion 105) formed by etching in a region corresponding to the display region. A desiccant layer 106 for absorbing moisture is coated in the pocket portion 105.
In the conventional sealing structure of the organic EL panel described above, however, flexure occurs in the device glass substrate 100 or the sealing glass substrate 104 by an external force so that the organic EL element comes into contact with the desiccant layer 10. Thus, the cathode 101 or an organic emissive layer below the cathode 101 is damaged.
Furthermore, the organic EL element is a self-emission device and generates heat when emitting light. This raises the temperature of the glass substrate having the organic EL element. The above conventional sealing structure is poor in heat dissipation so that the temperature rises rapidly. If the temperature rises, for example, to 60 degrees or higher, the life of the organic emissive material of the organic EL element is shortened.